When describing the contacts of a KIO module, the terms "potential-free" and "potential-loaded" appear. Disregarding them and connecting them incorrectly may lead to errors during operation or may destroy the device. In the following the terms are defined.
When connecting interfaces, a potential-free contact is usually always connected to a potential-loaded contact, i.e. one side is voltage-free, the other side is voltage-loaded.
If both sides are potential-free, the communication does not work. If, on the other hand, both sides are potential-loaded, in the worst case the device may be destroyed.
The I/O module 7017 has no potential-free or potential-loaded inputs. It has 8 analog inputs for measured values (0-10 V, 4-20 mA)
The I/O module 7052 has 8 digital inputs for circuits with potential.
The I/O module 7053 has 16 digital inputs for potential-free circuits.
You can find further information here IO-Module (KIO70xx)